1. Field of Use
This invention relates generally to die-cut self-adhesive flexible paint masking parts for masking curved surfaces of objects which are to be painted.
In particular, it relates to improvements in the configuration and construction of such a part to facilitate the application thereof to a curved surface and to ensure precise location of the part thereon.
2. Description of the Prior Art
In the automotive industry, conventional metal front and rear automobile bumpers are rapidly being replaced by molded plastic resilient bumpers, called "fascia", which are of complex design and configuration and have functional and decorative surfaces integrally formed therein. A typical fascia for the front end of an automobile body comprises an elongated main surface which extends across the front of the auto body and integrally formed short side surfaces which extend rearwardly for a short distance along opposite sides of the auto body. Typically, each short side surface is joined to the main surface by a sharply curved corner surface. A facia for the rear end of an auto body is similarly configured but is reversely disposed on the rear end of the auto body. Some fascia include a decorative portion which extends along the front of the main surface, around the sharply curved corner surfaces and along the short side surfaces of the facia. In some cases, lenses for parking lights may be located within or form part of the decorative portion. If, for practical or aesthetic reasons, the fascia is to be spray-painted but the decorative portion is not, it is necessary to apply masking tape and/or masking parts over the decorative portion prior to painting. It is imperative that the masking tape and masking parts, if used, be precisely and exactly located to assure an acceptable paint job. The masking tape can be applied in either of two ways: by successively tearing strips of masking tape from a roll and manually applying each strip along an appropriate section of the decorative portion, or by using a tape dispenser/applicator device to apply the masking tape along the major length of the decorative portion. The procedure of manually applying tape is time-consuming, labor-intensive, unduly costly, wasteful of tape, and sometimes results in misalignment of the side edges of two overlapping strips of tape thereby cauing an unsightly paint job. However, our co-pending U.S. patent application Ser. No. 165,818, filed on even date herewith and assigned to the same assignee as the present application, entitled "Apparatus For Dispensing and Applying Tape", discloses and claims a device for more efficiently and precisely applying tape along the major length of the decorative portion to be masked.
But, whether a strip of tape is applied manually or by means of a dispenser/applicator device, it is especially difficult to properly apply it around a sharply curved corner of a decorative portion. Therefore, it is preferable to employ a die-cut paint masking part which is specifically designed for masking a sharply curved corner.
Some presently available masking parts of this type are die-cut to a desired shape from a commercially available flat web which comprises a first sheet of flexible, paint-impervious masking material fabricated of suitable paper or plastic; a layer of pressure-sensitive adhesive material on the underside of the first sheet and permanently adhered thereto; and a second sheet of flexible material fabricated of suitable paper or plastic which is temporarily adhered to the adhesive layer to protect it but which can be stripped or peeled therefrom to expose the adhesive material.
A die-cut masking part cut from such a web comprises a mask with an adhesive layer on its underside and a removable protective liner for the adhesive layer and is employed as follows. First, prior to application of the mask to a sharply curved corner surface to be masked, a portion of the protective liner is manually peeled away from the adhesive material. Then, the mask is attached to the curved corner surface by the exposed adhesive. Finally, the remaining portion of the protective liner is peeled away and the remainder of the mask is manually pressed, shaped and folded to fit and adhere to the curved corner surface to be masked.
The following important factors must be taken into account when designing, fabricating and using die-cut mask. First, the outline of the die-cut mask part must be suitably designed and shaped to properly and effectively conform, before and after bending, shaping and folding, to the shape of the curved corner surface to which it is to be applied. Second, consideration must be given to how easily and efficiently the mask can be manually manipulated by the user after some or all of the protective liner has been peeled off and while the mask is being applied. The adhesive material on the underside of the mask is very tacky and mishandling can accidentally cause the mask to stick in the wrong place on the surface to be masked, or stick to the hands of the user, or even to itself. Usually, when this happens, the masking part must be discarded and a new one selected. This, of course, is wasteful of time, labor and material. Third, since the web from which the masking parts are die-cut is relatively expensive, it is desirable that the contour of the masking part be such that a maximum number of individual masking parts of desired size can be laid out and die-cut from a given area of the web, without sacrificing other design and contour considerations.
It is desirable, therefore, to provide improved die-cut paint masking parts which meet the aforementioned criteria and overcome the aforementioned drawbacks and have other advantages.